Wallachia or Walachia is a historical and geographical region of Romania. It is situated north of the Danube and south of the Southern Carpathians. Wallachia is sometimes referred to as Muntenia (Greater Wallachia), through identification with the larger of its two traditional sections; the smaller being Oltenia (Lesser Wallachia). Wallachia was founded as a principality in the early 14th century by Basarab I, after a rebellion against Charles I of Hungary, although the first mention of the territory of Wallachia west of the river Olt dates to a charter given to the voievod Seneslau in 1246 by Béla IV of Hungary. In 1417, Wallachia accepted the suzerainty of the Ottoman Empire; this lasted until the 19th century, albeit with brief periods of Russian occupation between 1768 and 1854. In 1859, Wallachia united with Moldavia (as United Principalities), to form the basis of the modern state of Romania, with Transylvania joining 59 years later (in 1918) to form the new Kingdom of Romania which was first established in 1881.